Speech privacy apparatus



N ov. 28, 1950 D. F. HoTH SPEECH PRIVACY APPARATUS Filed Feb. '7, 1947 patented Nov. 28, 1'950 SPEECHPRVACY'APBABA'IUS Daniel ElHoth, Englewood, Nr J.

ApplieationjFebruai-y 7, 1947 SeriaLNo. 72659.71

(Cl. L79"-1.5` )1 (Granted under. the,- aet of. March 3, 1883),; as; amended. April. 30, 192,8;l 370 0. G. 75.7,),

6, Claims.A

The intention described herein` may be manu facture@ arid-11,5661., .by or for the Government for governmental purposes, without thev payment to me 0f? any royalty thereon..

'.l-Thsinyentionis rin Communications; apparatusand,rxiore` particularly isiri speech oriyaey sys?A tema Sra/,eralA distinctlsinds of speech priyaey apriete ratus are known in the art. The present inyenf, tion is directed especially to that type which involves divisionoi the inputl lsignalen a time basis.; with scramloling or. rearrangement of the elements out of. their usual order before trans,

mission; and.. the principal object thereof. is. to

proyide- `a simpler speech Scrambler of the time division; typethangs known in the art.

Other objects willy be apparent from a reading 0f; the; following specicationand claims.

In the drawings:

Figure 1 shows in diagram the principal elements oi a transmitter embodying my special Slambling device;

Figure la is. detail partly in section of one means of mountingl a magnet element used in. the invention; and

Figure 2V is a` similar illustration of, the ele-vr ments of a receivngstation.

Referring to. the drawings andparticularly to, Eiglirel/ thereof Iis a disc adapted to be rotated in a ,clockwise direction atapredetermned :fixed speed bymeans of,A a motor I I and friction drive I.I. One. sector, I2. o fv the disc Il!` is plated, or otherwise provided with a magnetizablesurfaca whereas; the d iscv proper is formed of non-mag. netic; material',

Sector I2 is shown 90 in extent. Its angular lengthL in fact, will depend upon. the angle through. which the disc rotates during one time element.

Trie present description will for purposes of. simplicity assume a coding cycle of four elements onli/ It will be understood that a four-element coding. cycle will provide very low. security, and` tetes. beneath Mounted on, the guidiasJY one to each, guide, are four recording coils i211`v` 2 I ,A22,y and Each, of these coilsis locatedatL adiferent radial. distancefrom the centeroi the.y

disc, a. distance, which will be fixed .during cer-V TheA guides, of ccmrse.`r are..

tain intervals while recording: out which. should be: Yaliable atV the will of: an; operator. A slid-.e` able-spring-oressed mounting; will surnce., such a mounting is; ShwrrinlEigllre; la whereinv can te; seen. the guide;- memioer- I4 together withV a @operating-1 magnet: member 2li; The. record mg coil` assembly is proyidedwith ae, groove, Zill-Y in, the,y interior thereof, and. in one side thereoi isA a1. bent spring; :2p:t secured. in place by a 'pin or- SQreW adjustment-or spring; 2t? is; such: that.. it; will bear witdrsuocient. pressure. upon. guide t5. to: prevent casual displacement of. the assembly While permit-ting.intentional.movement; thereor.,

Thewilldirlgs 2 Il, 24h 22 andi 21a .are connected electrically series. and aref energized by means of the. output of; ampliijenzz. l With the;recordingzceilsinthepositions shown. 1t, can.; he-seenthatthefleading edgeof magneti@` ablesector I2 off disc; 1:0 willi. move: into the vieidi 0f Coil 211:. tust.. as; the trailingz edge, of; the sector moves` out; or the field` ooit. 2 3. There may bey asligritamountlot.overlapping*this:beingriininarl terial-but-,for practical purposes one; impression isimadelon sector lf2; duringv any one time intereval. Four iinpressionaN however, be made;- during oneflrevolntioniof; the disc since thea several coilsdeiinefseparete and distinotnathsg,

Erasingx coils; 25,: 26,v 2 1; and 2 are pairedwii'a.` each of. thev recording; coils.. that: each. onef in arrangedy in` thespathof.; a. differenti one. of recordingcoils, and; adjacent thex same, .sQ- that: each may eonditiorrla particular oath; on:- thedise;l before it passes. beneath a recording: coil-,t Tiles erasing. coils are mounted, on; guides oir-brackets; 29, 313;, 3l, ands32- vsolostantiallyflike the; guides already mentioiied.. r

Reprodiieing;eoilaofwhiohfourare,showni are; provided and bear thief reerenee charactorsA 34,V l5,v and` 35. 'linea-skool abe understoodznto beY connected in series .and te feed: inta output-- amplifier 50; Ehen too-are; adinstable. radiallaV preferablyei-ustasshow -Eig la;

Each of-theseeoils:is rangedascrthat: the. path 0f one ofi. thearecording: :magnets passes: directly thereunderflheexact relativa order of. theE reproducing magnets; deoendsfuponi theeode weicht is, to. be used-t te provide nriyauiyo in; communica-r tionsutilizingmxfinvention; As.: sh0wn, a speech; element impressed nponlmagnetizable; sector t2; by, recording coil; Lais picked un by reproducing; magnet 33; 135? laten. a. speech, element im pressed ate L willfbe reproduced=.at,34 225' later. A, Speechu element imnressed', at. 211 is.- picked-V up; again. tor transnriissionkv at` 28, also. 2259 laten,

A speech element impressed by magnet 23 is not reproduced for transmission until sector l2 reaches magnet 33, or 315 beyond.

It will be apparent that various codes, that is, arrangements of the speech elements relative to their normal order, are a function of the arrangement of recording and reproducing coils on their respective guides. Further, it is obvious that additional security or privacy will be obtained by using a code cycle more than four elements long, and it is entirely feasible to use a cycle much longer and then to provide means for modifying the cycle at intervals. These features form no part of the present invention.

The receiving disc 40 is in all substantial respects like sending disc I and comprises a disc proper with a magnetizable quadrant 4| therein. Any convenient means for synchronizing the two discs may be utilized. Recording coils 42, 43, 44, and 45 are just like coils 2B, 2|, 22, and 23 at the transmission station, and similar erasing coils are employed. Reproducing coils 46, 41, 48, and 49 also are like reproducing coils 33, 34, 35, and 3G.

The discs normally will not be in exact phase with each other. The amount of lag will vary with several circumstances, such as transmission delay, length of coding cycle, and so forth. The four-element system herein described requires a 45 lag on the part of the receiving disc with respect to the sending disc, assuming no delay in transmission, which merely vmeans that, as sector |2 of disc I0 reaches coil 25, sector 4| of disc 40 reaches reproducing coil 49.

Recording coils 42, 43, 44, and 45 are positioned in the same positions relative to their disc as 4recording coils 20, 2|, 22, and 23 with respect to disc Hl, and each is paired with an erasing coil, as 42'. Reproducing coils 4'6, 41, 48, and 49 are arranged in locations eiectively converse to the locations of reproducing coils 33, 34, 35, and 36. If, for example, reproducing coil 33 (#2 in the cycle) picks up the speech recorded by coil 2|] (#1. in the cycle) in the transmission station, then in the receiver, reproducing coil 46 (#1 in the cycle) must pick up the speech component recorded by coil 43 (#2 in the cycle). l

--The method of enciphering and deciphering speech according to a four-element codeis simple. Assuming that the sending and receiving discs are synchronized and that they are properly lzphased, the rst speech element appearing at the output of ampliiier 24 will appear simultaneously on the several windings 20, 2|, 22, and 23. At this time, however, only coil 2G will be eiective, for the magnetizable quadrant I2 of disc I0 is just beginning to pass therebeneath. As disc IB continues to rotate, the rst speech element will be replaced in all windings by the second element just in time to be impressed upon sector |2 by coil 2 l; A moment later the first speech element willbe picked up by winding 33, beforethe third element is impressed upo'n sector l2 by coil 22. The fourth speech element will be impressed upon the magnetizableA element by recorder 23 just before the second element is reproduced at 34.

'- The speech element impressed at 22 remains on sector |2 until the segmentv reaches reproducing coil 35. It is, therefore," carried over into the ysecond cycle, which begins when the outermost LII with respect to its several recording and reproducing elements that at the same instant the signal picked up by winding 36, for example, is impressed upon the recording circuit, the leading edge of magnetizable sector 4| passes into the field of Winding 44. Proper adjustment of the recording and reproducing elements will provide rescrambling of the transposed speech elements so that they are put upon output circuit 60 in proper order. The coils are shown in their proper positions with respect to the positions of the pickup and reproducing elements of the sending apparatus.

As has been explained, my apparatus is not restricted to privacy treatment involving only a four-element code, the only limitation in this respect being that or practicability in that for each coding element there must be (in the illustrated construction) a recording, an erasing, and a reproducing member. The angular width of the magnetizable disc sector will be equal to 360 divided by the number or" coding elements.

Furthermore, the foregoing description has been specically directed to the preferred embodiment of the invention in all respects, and many modications w-ll readily suggest themselves. Wherefore, for the true scope of the invention, reference should be had to the appended claims.

I claim:

1. In a speech privacy apparatus of the nature described, the combination of a disc, means for rotating said disc, a sector of magnetizable material mounted on said disc, a plurality of electrically connected recording members adjacent said disc for impressing signals on said sector said members being spaced about the surface of said disc at equal intervals the spacing of said members being dependent upon the angular length of said magnetizable sector and being arranged on radii of different lengths, and a plurality of electrically connected reproducing elements for picking up the impressed signals arranged at intervals equal to the intervals between said recording members and at similar distances from the center 0f the disc each said reproducing element being angularly spaced from a recording member with which it cooperates,

2. In a speech privacy apparatus of the nature described, a disc having a magnetizable sector of n degrees thereon, means for rotating said disc, a plurality of electrically connected recording members spaced at n degree intervals around the face of the disc and adjacent thereto at varying distances from the center thereof for impressing signals on said sector, and a plurality of electrically connected reproducing elements at n degree intervals for pickng up the impressed signal each spaced from the center of the disc a distance equal to the distance of one recording member from the center of the disc.

3. In a speech privacy apparatus of the nature described, a circular disc containing a quadrant of magnetizable material, four recording members connectedin seres adapted to have an input signal applied thereto said members being positionecl adjacent a face of said disc so as to be enabled to impress a signal upon said magnetizable segmentsaid members being spaced at intervals about the disc and at dilerent distances from the center thereof, and four reproducing elements spaced at 90 intervals atout said disc and adjacent thereto each at a distance from the center of the disc equal to the distance of a different one of said recording members from the center of 5 said disc said reproducing elements being electrically connected in series.

4. The invention of claim 3, further characterized by means for varying the positions of the said recording members relative to the center of said disc.

5. The invention of claim 3, further characterized by means for varying the positions of said reproducing elements relative to the center of said disc.

6. In a speech privacy apparatus of the nature described, a disc having a magnetizable sector thereon, means for rotating said disc, a plurality of electrically connected recording members equally spaced about the surface of said disc and adjacent thereto said members being at different radial distances from the center of said disc, a similar plurality of electrically connected reproducing elements equally spaced about the surface of said disc and between said recording members each of said elements being at a radial distance from the center of said disc equal to the radial distance of one of said members from the rality of erasing devices adapted to condition a path upon said sector before such path moves beneath a recording member.

DANIEL F. HOTH.

REFERENCES CITED The 'following references are of record in the filo of this patent:

`UNIIED STATES PATENTS Number Name Date 1,366,617 Wier et a1 Jan. 25, 1921 2,105,016 H. Smith Jan. 11, 1938 2,394,990 Eisler Feb. 19, 1946 2,461,464 Corderman June 4, 1946 2,401,888 J. Smith June 11, 1946 FOREIGN PATENTS Number Country Date 385,535 Great Britain Dec. 29, 1932 Certificate of Correction Patent No. 2,531,435

November 2E DANIEL F. HOTH It is hereby certified that error appears in the above numbered 3 requiring correction as follows:

In the drawing, Fig. 1, dise 10, should appear as shown below ir of as in the patentand that the said Letters read as corrected above, so th e same may conform to the record of the case in the Patent Oice.

Slgned and sealed this 20th day of February, A. D. 1951 [SEAL] THOMAS F. MURPHY,

Assistant 'ommz'ssz'oner of Patents.

Certicate of Correction Patent No. 2,531,435 November 28, 1950 DANIEL F. HOTI-I It is hereby certified that error appears in the above numbered patent requiring correction as follows:

In the drawing, Fig. 1, disc 10, should appear as shown below instead of as in the patentand that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oice.

Signed and Sealed this 20th day of February, A. D. 1951.

[SEAL] THOMAS F. MURPHY,

Assistant Uommz'ssz'oncr of Patents. 

